PayPal donation button won't work

I added the code from Paypal for my donation button. However when I preview the site and press the donation button it does nothing. No checkout appear when you press the donate button it just does nothing in site preview.

Here is my site Read-Only: LINK
(how to share your site Read-Only link)

Custom code does not render in preview. You need to look at the page on a published address to see it.